Railway crossing guard

ABSTRACT

A railway crossing guard includes a pivotable crossing gate and a set of retractable barriers on the same side of a set of railroad tracks. The pivotable crossing gate is mounted adjacent a first traffic lane to move between a lowered position and a raised position, and the retractable barriers are mounted in a line oriented parallel to the traffic lanes on a median strip between first and second traffic lanes. These retractable barriers move between a retracted position, in which the retractable barriers are substantially flush with the roadway, and an extended position, in which the retractable barriers are raised above the roadway. In the extended position, the retractable barriers are positioned to block a vehicle in front of the lowered crossing gate from crossing the median strip to drive around the lowered crossing gate.

BACKGROUND

[0001] The present invention relates to a railway crossing guard that provides improved security at relatively low cost.

[0002] Many approaches have been used for railway crossing guards. One commonly-used guard includes a pivotable crossing gate including an arm dimensioned to block a lane of traffic when the gate is pivoted to a lowered position. See for example U.S. Pat. 5,671,563. This approach often requires two crossing gates on each side of the railroad tracks, if both traffic lanes are to be blocked, and is therefore costly to implement.

[0003] Another approach is to use retractable barriers, such as those described in U.S. Pat. Nos. 5,975,792; 5,762,443; 5,425,595; 2,319,137; and Re 20,157. These retractable barriers are generally flush with the adjacent roadway when lowered, and they can be raised to block a lane of traffic.

[0004] On some occasions pivotable crossing gates have been used in combination with retractable barriers. In one case, a railway crossing guard included a pivotable crossing gate dimensioned to block a first traffic lane, and a line of retractable barriers positioned to block an adjacent traffic lane. This line of retractable barriers was positioned in the plane of movement of the pivotable crossing gate, such that a single vertical plane passing through the retractable barriers also passed through the pivotable crossing gate. This approach brings with it the disadvantage that the crossing-guard appears to entirely block the roadway, by the pivotable crossing gate for the first lane and by the retractable barriers for the second lane. This can impede emergency vehicle access to the adjacent railroad track.

[0005] The present invention is directed to an improved railway crossing guard that benefits from the economies of retractable barriers while overcoming this disadvantage of the prior art.

SUMMARY

[0006] The railway crossing guard described below includes a pivotable crossing gate and a line of retractable barriers. The crossing gate is mounted adjacent to a first traffic lane on a first side of the railroad tracks to move between a lowered position and a raised position, and this crossing gate has a length effective to block the first traffic lane but not the second traffic lane when the crossing gate is in the lowered position.

[0007] The retractable barriers are mounted on the median strip of the roadway, on the same side of the railroad tracks as the crossing gate. These retractable barriers move between a retracted position, in which the retractable barriers are substantially flush with the roadway, and an extended position, in which the retractable barriers are raised above the roadway. A controller lowers the crossing gate and extends the retractable barriers when a train approaches the roadway. In this position, the retractable barriers block a vehicle positioned in front of the lowered crossing gate from crossing the median strip to drive around the lowered crossing gate.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008]FIGS. 1 and 2 are perspective views of a first embodiment of the railway crossing guard of this invention in a traffic-blocking configuration (FIG. 1) and a standby configuration (FIG. 2).

[0009]FIG. 3 is a plan view of the crossing guard of FIGS. 1 and 2.

[0010]FIG. 4 is an exploded perspective view of one of the retractable barriers of FIGS. 1 through 3.

[0011]FIG. 5 is an exploded perspective view of the marker of FIG. 4.

[0012]FIG. 6 is an exploded perspective view of a portion of the drive mechanism of FIG. 4.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

[0013] Turning now to the drawings, FIGS. 1, 2 and 3 provide overall views of a railway crossing guard 10 that incorporates a preferred embodiment of this invention. For clarity of illustration, FIGS. 1 and 2 show a crossing gate 30 and retractable barriers 40 on one side only of the railroad tracks 20. The plan view of FIG. 3 shows a preferred arrangement, in which crossing gates 30 and retractable barriers 40 are provided on both sides of the railroad tracks 20.

[0014] The crossing guard 10 is mounted at a roadway 12 that includes first and second traffic lanes 14, 16 separated by a median strip 18. The pivotable crossing gate 30 and the set of retractable barriers 40 are positioned on the same side 22 of the railroad tracks 20. Though only a single lane 14, 16 is shown on each side of the median strip 18, in alternative embodiments there may be two or more lanes on each side of the median strip.

[0015] The illustrated median strip 18 is flush with the first and second traffic lanes 14, 16, but in general the shape and configuration of the median strip can vary widely. At one extreme, the median strip can simply be the central portion of the roadway 12 between the traffic lanes 14, 16, without any marking or elevation change to distinguish the median strip 18. Alternately, the median strip 18 may be marked, as for example with traffic lane markings, or it may be raised in whole or in part. All of these configurations are intended to be encompassed within the meaning of the term “median strip”. Similarly, the railroad tracks 20 can take any suitable form, and may include more than two rails.

[0016] The pivotable crossing gate 30 can be a conventional railway crossing gate that pivots between the lowered position shown in FIG. 1 and the raised position shown in FIG. 2. In the lowered position of FIG. 1, the pivotable crossing gate 30 extends across the first traffic lane 14 but not the second traffic lane 16. For this reason, a vehicle is physically able to bypass the pivotable crossing gate 30 by traveling in the second traffic lane 16 toward the railroad tack 20.

[0017] This invention can be implemented using the widest variety of pivotable crossing gates 30, and it is not limited to the particular form shown in the drawings. For example, the pivotable crossing gates shown in any of the following patents can be used, as can many alternatives to these examples: U.S. Pat. Nos. 3,994,457, 4,655,002, 4,666,108, 4,897,960, 5,442,878.

[0018] The retractable barriers 40 are moveable between an extended position (FIG. 1), in which the barriers 40 are raised above the roadway 12, and a retracted position (FIG. 2), in which the retractable barriers are lowered to a point where they are flush with the roadway 12. As shown in FIGS. 1, 2 and 3, the retractable barriers 40 are arranged along a line extending along the median strip 18, and they are positioned slightly upstream of the pivotable crossing gate 30 in the anticipated direction of traffic flow 42. In FIG. 1, the region 44 indicates schematically the location of a first vehicle in a line of vehicles stopped in front of the pivotable crossing gate 30. Note that the retractable barriers 40 are positioned alongside the region 44 to prevent a vehicle in the region 44 from crossing the median strip 18 and bypassing the pivotable crossing gate 30 in the second traffic lane 16. When the retractable barriers 40 are retracted and the pivotable crossing gate is raised as shown in FIG. 2, the roadway 12 is completely unobstructed and normal traffic flow (including cross-median traffic flow) is permitted.

[0019] A wide variety of retractable barriers can be used with this invention. By way of example, FIGS. 4 through 6 provide details of construction for one preferred retractable barrier.

[0020] As shown in FIG. 4, the retractable barrier 40 includes a marker 42 that is preferably sufficiently flexible to permit a vehicle to drive over the marker 42 in the extended position without fracturing it. The marker 42 is mounded for vertical movement in a marker-receiving tube 43, and the position of the marker 42 within the tube 43 is controlled by a reversible electric motor 44. Other types of motors, including hydraulic motors, can be used. The motor 44 is coupled to a lead screw 46 by a flexible coupling 50, shown in greater detail in FIG. 6. The lead screw 46 threadedly engages a lead screw nut 48 that is secured in place to an externally-threaded adapter 56. The adapter 56 includes notches 58 that slide along rails (not shown) of the tube 43 to prevent the adapter 56 from rotating with respect to the tube 43. For this reason, when the lead screw 46 is rotated by the motor 44, the adapter 56 moves vertically up or down as desired within the tube 43.

[0021] As shown in FIG. 5, the marker 42 includes an internally-threaded end piece 54 that threadedly engages the externally-threaded adapter 56. The adapter 56 supports a magnet 60 (FIG. 6), and the tube 43 supports magnetic sensors (not shown). These magnetic sensors respond to the magnet 60, thereby sensing when the marker 42 is in the retracted (flush) position as well as when the marker 42 is in the extended (raised) position. The marker-receiving tube 43 includes an upper flange that supports a annular wiper 52 that retards the introduction of road grit into the interior of the tube 43. A waterproof cord connection provides electrical power to and conducts sensor signals from the marker 40.

[0022] Other types of retractable markers can be used with this invention, including for example those described in the following U.S. Pat. Nos. 5,975,792; 5,762,443; 5,671,563; 2,319,137; and Re 20,157. This list is of course intended by way of illustration and should not limit the scope of this invention. In some cases, the lead screw may be replaced with a smooth rod, and the lead screw nut may be replaced with a set of rollers that perform the function of the lead screw nut while acting as an automatic clutch. Also, the magnet 60 and associated sensor may be replaced by a current sensor that monitors current drawn by the motor 44. An excessively high motor current may be taken as an indication that the marker has reached an extreme of travel.

[0023] Returning to FIG. 3, the crossing guard 10 also includes a controller 70 that responds to two crossing-approach sensors 72 and two crossing-exit sensors 74. When a train approaches the crossing, the respective crossing-approach sensor 72 sends a first command to the controller 70, which causes the controller 70 to lower the pivotable crossing gate 30 and to raise the retractable markers 40 to the position of FIG. 1. After the train has crossed the roadway 12, the respective crossing-exit sensor 74 sends a second command to the controller 70, which causes the controller 70 to raise the pivotable crossing gate 30 and to retract the retractable barriers 40 to the position of FIG. 2. The controller 70 and the sensors 72, 74 can take any suitable form. In one example, the controller 70 is implemented as a conventional programmable logic controller. Alternatively, a programmable microprocessor or any alternative structure, electrical or mechanical, can be used to achieve the control functions described above.

[0024] To improve visibility, the crossing gate 30 preferably includes warning lights that are activated when the crossing gate is lowered, and the markers 42 are preferably provided with a highly reflective coating or layer or with internal lights. As is conventional, warning bells or other warning devices can be used to alert the drivers of oncoming vehicles when the crossing gate 30 is lowered.

[0025] The crossing guard 10 described above provides a number of important advantages. First, by combining a pivotable crossing gate with retractable barriers, the overall cost of the crossing guard is reduced. Second, because the retractable barriers 40 are aligned with the median strip, a waiting vehicle is blocked from crossing the median strip to circumvent the lowered crossing gate. Third, the traffic lane that is not blocked by the pivotable crossing gate 30 remains unobstructed, thereby providing emergency vehicle access to the region of the railroad tracks 20 and an exit path for vehicles on the railroad tracks. As explained above, the markers 42 are preferably flexible barriers such that a vehicle can drive over the markers 42 when necessary. Nevertheless, they provide a visual barrier that may undesirably obstruct access of emergency vehicles if placed across the traffic lane opposite the crossing gate on a given side of the railroad tracks. Alternatively, the markers 42 may form rigid barriers.

[0026] In the foregoing example, the retractable barriers are completely flush with the roadway when retracted. Alternatively, the retractable barriers may protrude a small distance above the roadway surface when retracted. Such retractable barriers are considered to be substantially flush with the roadway as this term is used in the present specification.

[0027] The term “obstruct” is intended broadly to include physical obstruction (as for example by a rigid retractable post or bollard) as well as visual obstruction (as for example by a flexible marker). Thus, the marker 42 described above obstructs a vehicle from crossing the median strip, even though the vehicle is physically able to drive over the marker.

[0028] The term “barrier” is intended broadly to encompass rigid barriers and flexible barriers.

[0029] The foregoing detailed description has discussed only a few of the many forms that this invention can take. For this reason, this detailed description is intended by way of illustration and not limitation. It is only the following claims, including all equivalents, that are intended to define the scope of this invention. 

1. A railway crossing guard on a roadway comprising first and second parallel traffic lanes separated by a median strip, said traffic lanes crossing a set of railroad tracks, said crossing guard comprising: a pivotable crossing gate mounted adjacent the first traffic lane on a first side of the railroad tracks to move between a lowered position and a raised position, said crossing gate having a length effective to block the first traffic lane when the crossing gate is in the lowered position; a plurality of retractable barriers mounted on the median strip on the first side of the railroad tracks to move between a retracted position, in which the retractable barriers are substantially flush with the roadway, and an extended position, in which the retractable barriers are raised above the roadway; said retractable barriers, when in the extended position, positioned to obstruct a vehicle positioned in front of the lowered crossing gate from crossing the median strip to drive around the lowered crossing gate.
 2. The invention of claim 1 wherein each retractable barrier comprises an elongated marker, a marker-receiving tube, and a motor coupled to the marker to retract the marker into the tube and to extend the marker out of the tube.
 3. The invention of claim 2 wherein the marker is sufficiently flexible to permit the vehicle to drive over the extended marker without fracturing the marker.
 4. The invention of claim 1 further comprising: a controller responsive to a first command (1) to lower the crossing gate, and (2) to extend the retractable barriers.
 5. The invention of claim 1 wherein the controller is responsive to a second command (1) to raise the crossing gate, and (2) to retract the retractable barriers.
 6. The invention of claim 1 wherein the crossing gate is disposed substantially entirely on one side of the median strip when in the lowered position.
 7. The invention of claim 1 wherein the crossing gate blocks the first traffic lane but not the second traffic lane in the lowered position.
 8. The invention of claim 1 wherein the plurality of retractable barriers comprises at least three retractable barriers mounted in a line extending along the median strip. 